On 2016/9/27 18:57, Greg Kroah-Hartman wrote: > On Sat, Sep 24, 2016 at 05:14:25PM +0800, Kefeng Wang wrote: >> Declare an OF early console for SBSA UART so that the early console device >> can be specified via the "stdout-path" property in device-tree. >> >> Cc: Russell King <li...@armlinux.org.uk> >> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> >> Signed-off-by: Kefeng Wang <wangkefeng.w...@huawei.com> >> --- >> drivers/tty/serial/amba-pl011.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/tty/serial/amba-pl011.c >> b/drivers/tty/serial/amba-pl011.c >> index 7d9b291..3688d3b 100644 >> --- a/drivers/tty/serial/amba-pl011.c >> +++ b/drivers/tty/serial/amba-pl011.c >> @@ -2330,6 +2330,7 @@ static int __init pl011_early_console_setup(struct >> earlycon_device *device, >> return 0; >> } >> OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup); >> +OF_EARLYCON_DECLARE(pl011, "arm,sbsa-uart", pl011_early_console_setup); > > Why do you need another option for the same thing?
It is used to support earlycon(without option) for sbsa-uart in bootargs. chosen { stdout-path = "serial0:115200n8"; bootargs = "earlycon" }; uart0: uart@602b0000 { compatible = "arm,sbsa-uart"; reg = <0x0 0x602b0000 0x0 0x1000>; ... }; We setup a unique struct with compatible name by OF_EARLYCON_DECLARE, #define OF_EARLYCON_DECLARE(_name, compat, fn) \ static const struct earlycon_id __UNIQUE_ID(__earlycon_##_name) \ __used __section(__earlycon_table) \ = { .name = __stringify(_name), \ .compatible = compat, \ .setup = fn } if without this patch(see drivers/of/fdt.c), early_init_dt_scan_chosen_serial() - for (match = __earlycon_table; match < __earlycon_table_end; match++) -- if (fdt_node_check_compatible(fdt, offset, match->compatible)) countinue; -- of_setup_earlycon(match, offset, options); // will never touch here. Thanks, Kefeng > > confused, > > greg k-h > > . >